Picard is the next generation MusicBrainz tagging application. This new 
tagging concept is album oriented, as opposed to track/file oriented like 
the ClassicTagger was. Picard is written in Python, which is a cross-platform 
language, and makes use of cross-platform libraries - this allows the same 
code to run both on Windows, Linux and Mac OS X.

This requires mutagen, and libofa is optional but recommended.
